The long-term objective of this project is to arrive at an understanding of how the nervous system generates behavior and how the neuronal circuits responsible for this function arise during ontogeny. The experimental material on which these studies are to be carried out is the nervous system of leeches, the class of blood-sucking worms belonging to the annelid phylum. We plan to carry out anatomical and electrophysiological studies of the embryological development of the leech nervous system. For this purpose we have started laboratory culture of suitable leech species, namely Helobdella stagnalis and Haementaria ghilianii.